MITF-Independent Melanocyte Progenitors are Highly Susceptible to GNAQ-induced Uveal Melanoma in Adult Zebrafish

Melanocytes reside in diverse microenvironments that influence their susceptibility to oncogenic transformation, however, studying rare melanoma subsets has been hindered by the lack of suitable animal models. We developed a primary, immune-competent zebrafish model to study uveal melanoma (UM), utilizing choroidal-targeted injection and electroporation of plasmids containing human GNAQQ209L and CRISPR/Cas9 cassettes for tumor suppressor gene deletion. Single-cell transcriptional profiling of genetically identical eye- and skin-derived tumors revealed distinct oncogenic pathways, highlighting the importance of studying melanoma subtypes in their correct anatomical context. Additionally, we identified a population of tfec- and pax3a-expressing melanocyte progenitor cells in mitfa-deficient embryos and adult zebrafish eyes, which were highly susceptible to GNAQ-driven transformation. While previous studies have linked mitfa deficiency to accelerated UM onset, our findings suggest that an expanded progenitor population in mitfa-deficient animals drives this susceptibility. Our study establishes a critical role for Mitfa-independent melanocyte progenitors in UM pathogenesis HighlightsO_LIChoroid-targeted electroporation of oncogenic GNAQ induces anatomically correct UM in adult zebrafish. C_LIO_LIMitfa-independent melanocyte progenitor cells are highly susceptible to GNAQ-driven transformation. C_LIO_LIGermline loss of mitfa accelerates UM onset via progenitor enrichment, a phenotype not recapitulated by conditional mitfa-KO in adult zebrafish. C_LIO_LIOncogenic BRAF and GNAQ transform molecularly and developmentally distinct subpopulations of cells within the melanocyte lineage. C_LI